Recently, a plasma display apparatus has become an attractive subject as a display panel (flat display device) with excellent visibility; and the technology is steadily advancing for large-sized screen with high definition.
The plasma display panels are roughly divided into AC powered and DC powered in driving method, and into surface discharge and counter discharge in discharging method. Currently, however, surface discharge AC powered structure has become a mainstream technology from a view point of high definition, large screen and simplified manufacturing method.
Now, a structure of the plasma display panel used in the plasma display apparatus is described with reference to FIG. 8.
A plurality of arrays of stripe shaped display electrodes 2 comprised of a paired scan electrode and sustain electrode are formed on transparent front substrate 1 composed of glass or the like. Dielectric layer 3 is formed to cover the arrays of the electrodes, and protective layer 4 is formed on dielectric layer 3.
A plurality arrays of stripe shaped address electrodes 7 covered by overcoat layer 6 are formed on rear substrate 5, placed to face against front substrate 1, to cross display electrodes 2 comprised of scan electrodes and sustain electrodes. A plurality of ribs 8 are provided on overcoat layer 6 parallel to and between address electrodes 7, and fluorescent layers 9 are applied on side surfaces of ribs 8 and on surfaces of overcoat layer 6.
These substrate 1 and substrate 5 are positioned to face each other so that display electrodes 2 comprised of scan electrodes and sustain electrodes intersect address electrodes 7 at approximately right angles to form a narrow discharge space sandwiched between these substrates, and are sealed in surrounding peripheries. The discharge space is filled with one of rare gases, such as Helium, Neon, Argon or Xenon, or a mixture of them, as a discharge gas. The discharge space divided into a plurality of partitions by ribs 8 creates a plurality of tiny discharge cells where intersection points of display electrodes 2 and address electrodes 7 are located, and each discharge cell is provided with one of fluorescent layers 9 of red, green and blue in this order.
FIG. 9 illustrates a wiring diagram of electrodes arrangements for the plasma display panel used in the plasma display apparatus. Pairs of scan electrode and sustain electrode, and address electrodes form an M times N matrix array that has scan electrode codes of SCN 1 to SCN M and sustain electrode codes of SUS 1 to SUS M arranged in row directions, and address electrode codes of D 1 to D N arranged in column directions.
In the plasma display panel with electrodes arranged as discussed above, a writing pulse supplied between an address electrode and a scan electrode generates address discharge between address electrode and scan electrode. Selecting suitable discharge cells, a sustaining discharge then starts between scan electrode and sustain electrode to show a required display by applying on alternative, periodically flipping sustaining pulse on the scan electrode and sustain electrode.
The plasma display apparatus employing a plasma display panel of above structure has such a configuration that the panel fixed on front side of a chassis and driving circuitries mounted on back side of the chassis are included in the housing comprised of a front frame and a back cover (See JP. Pat. No. 2,807,672).
However, the plasma display apparatus has had a drawback to cause audible noises when low-cost iron instead of aluminum is used for the back cover.
The higher audible noises occur in low AC supply of 100 V in Japan and 120 V in US compared with high AC supply of 200 to 240 V as the input current becomes larger.
In particular, the problem is that the phenomenon becomes worse in plasma display apparatus using an AC/DC rectifier with a capacitor input type filter.